Among generally-used control systems for controlling control objects such as plant equipment, there is a control system which is formed from multiple control apparatuses connected together via a network and controls the plant equipment by transferring control information among the control apparatuses via the network.
There is another control system which monitors the plant equipment by collecting data, such as process values, from the control apparatuses via the network.
There has been an idea that: a control system stores data on control of the plant equipment; and, for example, when an abnormal condition occurs in the plant equipment, the stored data are analyzed for use to examine causes of the occurrence of the abnormal condition, and to make plans about how to deal with the abnormal condition. To realize the idea, data need to be quickly collected from the control apparatuses.
Patent Document 1 has proposed a data collection apparatus for an iron and steel plant system which is configured to: collect binary data of control information outputted from a control apparatus to an iron and steel plant; collect binary data of event information on the iron and steel plant controlled by use of the control information outputted from the control apparatus; add a common key to the binary data of the control information and the binary data of the event information which are collected at the same time; accumulate the binary data of the control information together with the attached common keys; and accumulate the binary data of the event information together with the attached common keys.